Many people believe that even with a ratty car, a high octane fuel will boost its little engine so it run faster, better, and basically kick-butt in the street-racing world.
Not necessarily. The only thing a high octane fuel can do is to make the fuel more “resistant to knocking.” Knocking, also called pinging, happens when the combustion chamber ignites prematurely. While this is rarely affects the car’s performance, really loud knocking can actually cause a car’s engine to break down.
To solve this problem, the composition of high-octane fuel makes it harder to ignite. This avoids premature or early ignition, which is the root of “knocking” issues. So contradictory to the perception that high-octane fuel is more powerful, it’s just more resistant.
Most cars don’t need high-octane fuel. In fact, engines will run at peak performance on standard octane—or at least, “peak” as defined by the car’s model and manufacturer. The only cars that really need high-octane fuel are race cars (which use super high-octane fuel which are only seen at race tracks) or high-performance sports cars. To be sure, check the owner’s manual.
Other people think that high-octane fuel leaves less deposits or, in some way, “cleans” the engine. In reality, almost every kind of fuel being sold today contains some kind of cleaning additives.
So what’s the benefit of spending extra money on high octane fuel? In one word, none. It won’t even solve the “pinging” or “knocking” you may hear in your car. Save the money on fuel and use it to bring the car to a mechanic instead.